Transistors - Bipolar (BJT)

Transistors - Bipolar (BJT) - Single

Part Number	Description / PDF	Quantity
MPS3563RLRA	SMALL SIGNAL BIPOLAR TRANSISTOR	6000
2SA1037AKT146S ROHM Semiconductor	TRANS PNP 50V 0.15A SMT3 TR	2575
BDW94C STMicroelectronics	TRANS PNP DARL 100V 12A TO-220	3297
BCX70JE6433HTMA1 IR (Infineon Technologies)	TRANS NPN 45V 100MA SOT23-3	60000
MJD32CTF-ON	POWER BIPOLAR TRANSISTOR	219371
ZTX753STZ Zetex Semiconductors (Diodes Inc.)	TRANS PNP 100V 2A E-LINE	1050
PMBTA06/6215 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	3264000
KSE44H11TU	POWER BIPOLAR TRANSISTOR	0
KSB744YSTU	TRANS PNP 45V 3A TO126-3	1918
PHPT60415NY115 NXP Semiconductors	POWER BIPOLAR TRANSISTOR NPN	51000
KSC1845PTA	TRANS NPN 120V 50MA TO92-3	795092
BC56-16PAS115 NXP Semiconductors	SMALL SIGNAL BIPOLAR TRANSISTOR	0
NTE238 NTE Electronics, Inc.	TRANS NPN 750V 8A TO3	71
CXT5401 TR PBFREE Central Semiconductor	TRANS PNP 150V 0.6A SOT-89	161
BC548B B1G TSC (Taiwan Semiconductor)	TRANSISTOR, NPN, 30V, 0.1A, 200A	0
BC807K-40VL Nexperia	45V, 500MA PNP GENERAL PURPOSE	60000
MMBT3906-ON	0.2A, 40V, PNP	976484
KSA940H2TU	TRANS PNP 150V 1.5A TO220-3	54227
2SD1627-TD-E	NPN SILICON TRANSISTOR	8000
BC857BR13 Diotec Semiconductor	BJT SOT-23 45V 100MA	0

Transistors - Bipolar (BJT) - Single

1. Overview

Bipolar Junction Transistors (BJTs) are three-terminal semiconductor devices that use both electron and hole charge carriers. They form the foundation of analog electronics through their ability to amplify signals and control current flow. BJTs remain critical in modern electronics for applications ranging from audio amplifiers to power management circuits, offering superior linearity and robustness in switching operations.

2. Main Types & Functional Classification

Type	Functional Characteristics	Application Examples
NPN Transistor	Majority carriers: electrons. Requires positive base current for conduction.	Low-noise amplifiers, digital logic circuits
PNP Transistor	Majority carriers: holes. Conducts with negative base current.	Power supply circuits, motor controllers
High-Frequency BJT	Optimized for RF/microwave signal amplification (f_T > 100 MHz)	Wireless communication systems, radar
Power BJT	High current/voltage ratings (I_C > 1A, V_CE > 50V)	Switch-mode power supplies, motor drives

3. Structure & Composition

BJTs consist of three doped semiconductor regions forming two p-n junctions:

Emitter: Heavily doped region emitting charge carriers
Base: Thin, lightly doped middle region controlling carrier flow
Collector: Moderately doped region collecting carriers

Manufactured using silicon (common) or germanium (historic) with planar processing technology. The structure forms either NPN (n-type emitter/base/collector) or PNP configuration, with metal contacts for external connections.

4. Key Technical Specifications

Parameter	Description	Importance
Current Gain (h_FE)	Ratio of collector to base current (10-1000)	Determines amplification capability
Transition Frequency (f_T)	Frequency at which current gain drops to 1	Limits high-frequency performance
Max Collector Current (I_Cmax)	Maximum allowable continuous collector current	Defines power handling capability
Breakdown Voltage (V_CEO)	Max voltage between collector and emitter	Prevents device failure under stress
Saturation Voltage (V_CEsat)	Voltage drop in fully conducting state	Affects power efficiency in switching

5. Application Areas

Consumer Electronics: Audio amplifiers, LED drivers
Automotive: Engine control units, electric vehicle inverters
Industrial: PLCs, motor controllers
Telecommunications: RF power amplifiers, fiber optic transceivers
Aerospace: Avionics systems, satellite transponders

6. Leading Manufacturers & Products

Manufacturer	Product Series	Key Specifications	Typical Use
ON Semiconductor	2N3904	hFE: 100-300, fT: 300 MHz	General-purpose switching
Infineon	BC547	VCEO: 50V, ICmax: 100mA	Analog signal amplification
STMicroelectronics	2SD2656	ICmax: 15A, VCEO: 80V	Power inverter applications
Diodes Inc.	BFR93A	fT: 10 GHz, Noise Figure: 2dB	High-frequency front-end amplifiers

7. Selection Guidelines

Determine operating frequency: Select fT > 3 target frequency
Power requirements: Ensure Icmax and VCEO exceed circuit requirements by 20%
Thermal considerations: Calculate power dissipation (P=V_CE I_C)
Package type: TO-92 for low power, TO-220 for high-power applications
Environmental factors: Consider temperature ratings for industrial/military use

8. Industry Trends

Future developments include:

High-frequency BJTs operating beyond 100 GHz for 6G communication
Integrated BJT-MOSFET hybrid devices (BiCMOS) for mixed-signal applications
Wide-bandgap materials (SiC/GaN) for higher power density
Miniaturization through chip-scale packaging
Improved thermal management solutions for automotive applications